1. Field of the Invention
The present invention relates to a built-in wireless module for handheld electronic device and more particularly, to a wireless module with integrated antenna by using rigid-flex board having the characteristics of small size, low loss, low cost, and design and optimization facilitation.
2. Description of the Related Art
With new advances in technology, all kinds of handheld electronic products are used widely and developed with the tread toward deeper integration and smaller handheld sizes. In consequence, built-in electronic communication module is inevitably developed towards the same trend.
Conventional wireless module designs commonly have the communication IC and the antenna be mounted in one single printed circuit board. This design has the drawback of large size, not facilitating locational optimization of the antenna. Therefore, this design is not suitable for use in a small-sized electronic product. In order to eliminate this problem, another prior art design of wireless module was created. This prior art design uses a RF connector and a cable to connect separated communication IC and antenna, facilitating optimization of the antenna in the internal space of the electronic product. However, according to this design, the RF connector and the cable must use special materials and design techniques to reduce high-frequency loss, resulting in significant increase in component costs. A pin connector can be used to substitute for the aforesaid RF connector and cable for high-frequency loss reduction, however the impedance matching problem in signal transmission greatly increase the degree of design difficulty.
In view of the above-mentioned problems, U.S. Pat. No. 8,344,955 discloses a wireless module, entitled “Integrated antenna with e-flex technology”. This design enables a communication IC and an antenna to be respectively mounted in a rigid PC board and a flex PC board, wherein the flex PC board has at least one part thereof joined to one end of the rigid PC board to constitute a rigid-flex board. However, because the power layer and the ground layer are interruptedly mounted in the rigid PC board and a flex PC board, this design not only increases circuit complexity, but also may introduce unnecessary noises. Therefore, there is still room for improvement.